S-90550A860 5/16"-18 x 1 1/2" ASME B18.3, ASTM F879, MIL-DTL-18240 Venting Stainless Steel Hex-Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance thanks to 18-8 stainless steel construction, ideal for harsh environments and long-term reliability.
• High-strength, precision threads with Class 3A fit and UNC coarse spacing ensure secure, vibration-resistant fastening in demanding applications.
• Efficient installation and removal with a 3/16" hex drive, providing excellent torque transfer and reducing tool slippage.
• Flush, professional finish achieved with an 82° countersink angle and standard flat head profile for seamless surface integration.
• Enhanced pressure equalization via the vented design (0.078" vent diameter), preventing pressure buildup and potential failure.
• Full threading along the 1-1/2" length offers maximum grip and adjustability across the entire fastener.
• Rigorous quality assurance through compliance with ASME B18.3, ASTM F879, and MIL-DTL-18240 standards, ensuring consistent performance.

Professional Applications & Engineering Value

This 5/16"-18 UNC flat head screw is engineered to address critical challenges in industrial and mechanical assemblies. Its 18-8 stainless steel composition provides excellent resistance to corrosion and oxidation, making it suitable for outdoor, marine, and chemical-exposed settings. The fully threaded design and Class 3A thread fit deliver superior clamping force and vibration resistance, reducing the risk of loosening under dynamic loads. The hex drive allows for high-torque application with common tools, speeding up installation in tight spaces. Additionally, the vented feature mitigates pressure differentials, which is crucial in sealed systems or environments with temperature fluctuations. Ideal for machinery, automotive, and structural applications, this screw ensures durability and reliability where failure is not an option.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including UNC coarse threads with a Class 3A thread fit for tight tolerances and consistent performance. It meets ASME B18.3, ASTM F879, and MIL-DTL-18240 specifications, guaranteeing manufacturing excellence. Furthermore, it is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material restrictions are met for global industrial use.